Tylan's probably a good thing to have on hand anyway (and thanks for reminding me! I've been meaning to put together a first aid kit for the rat room), but changing the bedding should do the trick if you're using carefresh. Kiln dried pine just works a lot better if you're keeping anything more than a pair of pet rats. I think it smells better too, and the only lice outbreak I ever had was while using carefresh (no new rats or anything, there were lice or lice eggs in the bedding).